Rollup merge of rust-lang#124183 - compiler-errors:unnecessary-by-ref…

…, r=oli-obk

Stop taking `ParamTy`/`ParamConst`/`EarlyParamRegion`/`AliasTy` by ref

It's unnecessary and is annoying when we have it by value.

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1320,7 +1320,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             .into_iter()
             .map(|err| match err.obligation.predicate.kind().skip_binder() {
                 PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
-                    match predicate.self_ty().kind() {
+                    match *predicate.self_ty().kind() {
                         ty::Param(param_ty) => Ok((
                             generics.type_param(param_ty, tcx),
                             predicate.trait_ref.print_only_trait_path().to_string(),

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1070,7 +1070,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     // LL | blk();
                     //    | ----- this value implements `FnOnce`, which causes it to be moved when called
                     // ```
-                    if let ty::Param(param_ty) = self_ty.kind()
+                    if let ty::Param(param_ty) = *self_ty.kind()
                         && let generics = self.infcx.tcx.generics_of(self.mir_def_id())
                         && let param = generics.type_param(param_ty, self.infcx.tcx)
                         && let Some(hir_generics) = self

compiler/rustc_hir_typeck/src/expr.rs

@@ -2697,7 +2697,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     fn point_at_param_definition(&self, err: &mut Diag<'_>, param: ty::ParamTy) {
         let generics = self.tcx.generics_of(self.body_id);
-        let generic_param = generics.type_param(&param, self.tcx);
+        let generic_param = generics.type_param(param, self.tcx);
         if let ty::GenericParamDefKind::Type { synthetic: true, .. } = generic_param.kind {
             return;
         }

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -2144,7 +2144,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let callee_ty = callee_ty.peel_refs();
             match *callee_ty.kind() {
                 ty::Param(param) => {
-                    let param = self.tcx.generics_of(self.body_id).type_param(&param, self.tcx);
+                    let param = self.tcx.generics_of(self.body_id).type_param(param, self.tcx);
                     if param.kind.is_synthetic() {
                         // if it's `impl Fn() -> ..` then just fall down to the def-id based logic
                         def_id = param.def_id;

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -125,11 +125,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let Some(arg_ty) = args[0].as_type() else {
                     return false;
                 };
-                let ty::Param(param) = arg_ty.kind() else {
+                let ty::Param(param) = *arg_ty.kind() else {
                     return false;
                 };
                 // Is `generic_param` the same as the arg for this trait predicate?
-                generic_param.index == generics.type_param(&param, tcx).index
+                generic_param.index == generics.type_param(param, tcx).index
             } else {
                 false
             }
@@ -156,10 +156,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return false;
         }
 
-        match ty.peel_refs().kind() {
+        match *ty.peel_refs().kind() {
             ty::Param(param) => {
                 let generics = self.tcx.generics_of(self.body_id);
-                let generic_param = generics.type_param(&param, self.tcx);
+                let generic_param = generics.type_param(param, self.tcx);
                 for unsatisfied in unsatisfied_predicates.iter() {
                     // The parameter implements `IntoIterator`
                     // but it has called a method that requires it to implement `Iterator`
@@ -3232,9 +3232,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .sort_by_key(|&info| (!info.def_id.is_local(), self.tcx.def_path_str(info.def_id)));
             candidates.dedup();
 
-            let param_type = match rcvr_ty.kind() {
+            let param_type = match *rcvr_ty.kind() {
                 ty::Param(param) => Some(param),
-                ty::Ref(_, ty, _) => match ty.kind() {
+                ty::Ref(_, ty, _) => match *ty.kind() {
                     ty::Param(param) => Some(param),
                     _ => None,
                 },
@@ -3429,7 +3429,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 } else {
                                     param_type.map_or_else(
                                         || "implement".to_string(), // FIXME: it might only need to be imported into scope, not implemented.
-                                        ToString::to_string,
+                                        |p| p.to_string(),
                                     )
                                 },
                             },

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2371,7 +2371,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
             // type_param_sugg_span is (span, has_bounds)
             let (type_scope, type_param_sugg_span) = match bound_kind {
-                GenericKind::Param(ref param) => {
+                GenericKind::Param(param) => {
                     let generics = self.tcx.generics_of(generic_param_scope);
                     let def_id = generics.type_param(param, self.tcx).def_id.expect_local();
                     let scope = self.tcx.local_def_id_to_hir_id(def_id).owner.def_id;

compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs

@@ -28,7 +28,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         match err {
             ArgumentSorts(values, _) | Sorts(values) => {
-                match (values.expected.kind(), values.found.kind()) {
+                match (*values.expected.kind(), *values.found.kind()) {
                     (ty::Closure(..), ty::Closure(..)) => {
                         diag.note("no two closures, even if identical, have the same type");
                         diag.help("consider boxing your closure and/or using it as a trait object");
@@ -452,7 +452,7 @@ impl<T> Trait<T> for X {
                     }
                     (ty::FnPtr(sig), ty::FnDef(def_id, _))
                     | (ty::FnDef(def_id, _), ty::FnPtr(sig)) => {
-                        if tcx.fn_sig(*def_id).skip_binder().unsafety() < sig.unsafety() {
+                        if tcx.fn_sig(def_id).skip_binder().unsafety() < sig.unsafety() {
                             diag.note(
                                 "unsafe functions cannot be coerced into safe function pointers",
                             );
@@ -527,7 +527,7 @@ impl<T> Trait<T> for X {
         diag: &mut Diag<'_>,
         msg: impl Fn() -> String,
         body_owner_def_id: DefId,
-        proj_ty: &ty::AliasTy<'tcx>,
+        proj_ty: ty::AliasTy<'tcx>,
         ty: Ty<'tcx>,
     ) -> bool {
         let tcx = self.tcx;
@@ -541,7 +541,7 @@ impl<T> Trait<T> for X {
         };
         // Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
         // This will also work for `impl Trait`.
-        let ty::Param(param_ty) = proj_ty.self_ty().kind() else {
+        let ty::Param(param_ty) = *proj_ty.self_ty().kind() else {
             return false;
         };
         let generics = tcx.generics_of(body_owner_def_id);
@@ -598,7 +598,7 @@ impl<T> Trait<T> for X {
     fn expected_projection(
         &self,
         diag: &mut Diag<'_>,
-        proj_ty: &ty::AliasTy<'tcx>,
+        proj_ty: ty::AliasTy<'tcx>,
         values: ExpectedFound<Ty<'tcx>>,
         body_owner_def_id: DefId,
         cause_code: &ObligationCauseCode<'_>,
@@ -709,7 +709,7 @@ fn foo(&self) -> Self::T { String::new() }
         &self,
         diag: &mut Diag<'_>,
         msg: impl Fn() -> String,
-        proj_ty: &ty::AliasTy<'tcx>,
+        proj_ty: ty::AliasTy<'tcx>,
         ty: Ty<'tcx>,
     ) -> bool {
         let tcx = self.tcx;

compiler/rustc_middle/src/ty/generics.rs

@@ -263,7 +263,7 @@ impl<'tcx> Generics {
     /// Returns the `GenericParamDef` associated with this `EarlyParamRegion`.
     pub fn region_param(
         &'tcx self,
-        param: &ty::EarlyParamRegion,
+        param: ty::EarlyParamRegion,
         tcx: TyCtxt<'tcx>,
     ) -> &'tcx GenericParamDef {
         let param = self.param_at(param.index as usize, tcx);
@@ -274,7 +274,7 @@ impl<'tcx> Generics {
     }
 
     /// Returns the `GenericParamDef` associated with this `ParamTy`.
-    pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
+    pub fn type_param(&'tcx self, param: ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
         let param = self.param_at(param.index as usize, tcx);
         match param.kind {
             GenericParamDefKind::Type { .. } => param,
@@ -286,7 +286,7 @@ impl<'tcx> Generics {
     /// `Generics`.
     pub fn opt_type_param(
         &'tcx self,
-        param: &ParamTy,
+        param: ParamTy,
         tcx: TyCtxt<'tcx>,
     ) -> Option<&'tcx GenericParamDef> {
         let param = self.opt_param_at(param.index as usize, tcx)?;
@@ -297,7 +297,7 @@ impl<'tcx> Generics {
     }
 
     /// Returns the `GenericParamDef` associated with this `ParamConst`.
-    pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
+    pub fn const_param(&'tcx self, param: ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
         let param = self.param_at(param.index as usize, tcx);
         match param.kind {
             GenericParamDefKind::Const { .. } => param,

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1276,7 +1276,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 
     fn pretty_print_inherent_projection(
         &mut self,
-        alias_ty: &ty::AliasTy<'tcx>,
+        alias_ty: ty::AliasTy<'tcx>,
     ) -> Result<(), PrintError> {
         let def_key = self.tcx().def_key(alias_ty.def_id);
         self.path_generic_args(
@@ -3204,7 +3204,7 @@ define_print_and_forward_display! {
 
     ty::AliasTy<'tcx> {
         if let DefKind::Impl { of_trait: false } = cx.tcx().def_kind(cx.tcx().parent(self.def_id)) {
-            p!(pretty_print_inherent_projection(self))
+            p!(pretty_print_inherent_projection(*self))
         } else {
             // If we're printing verbosely, or don't want to invoke queries
             // (`is_impl_trait_in_trait`), then fall back to printing the def path.

compiler/rustc_middle/src/ty/sty.rs

@@ -1379,7 +1379,7 @@ impl<'tcx> ParamTy {
         Ty::new_param(tcx, self.index, self.name)
     }
 
-    pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
+    pub fn span_from_generics(self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
         let generics = tcx.generics_of(item_with_generics);
         let type_param = generics.type_param(self, tcx);
         tcx.def_span(type_param.def_id)

compiler/rustc_middle/src/ty/util.rs

@@ -432,19 +432,19 @@ impl<'tcx> TyCtxt<'tcx> {
             .filter(|&(_, k)| {
                 match k.unpack() {
                     GenericArgKind::Lifetime(region) => match region.kind() {
-                        ty::ReEarlyParam(ref ebr) => {
+                        ty::ReEarlyParam(ebr) => {
                             !impl_generics.region_param(ebr, self).pure_wrt_drop
                         }
                         // Error: not a region param
                         _ => false,
                     },
-                    GenericArgKind::Type(ty) => match ty.kind() {
-                        ty::Param(ref pt) => !impl_generics.type_param(pt, self).pure_wrt_drop,
+                    GenericArgKind::Type(ty) => match *ty.kind() {
+                        ty::Param(pt) => !impl_generics.type_param(pt, self).pure_wrt_drop,
                         // Error: not a type param
                         _ => false,
                     },
                     GenericArgKind::Const(ct) => match ct.kind() {
-                        ty::ConstKind::Param(ref pc) => {
+                        ty::ConstKind::Param(pc) => {
                             !impl_generics.const_param(pc, self).pure_wrt_drop
                         }
                         // Error: not a const param

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -124,7 +124,7 @@ pub fn suggest_restriction<'tcx, G: EmissionGuarantee>(
     msg: &str,
     err: &mut Diag<'_, G>,
     fn_sig: Option<&hir::FnSig<'_>>,
-    projection: Option<&ty::AliasTy<'_>>,
+    projection: Option<ty::AliasTy<'_>>,
     trait_pred: ty::PolyTraitPredicate<'tcx>,
     // When we are dealing with a trait, `super_traits` will be `Some`:
     // Given `trait T: A + B + C {}`
@@ -142,7 +142,7 @@ pub fn suggest_restriction<'tcx, G: EmissionGuarantee>(
     let generics = tcx.generics_of(item_id);
     // Given `fn foo(t: impl Trait)` where `Trait` requires assoc type `A`...
     if let Some((param, bound_str, fn_sig)) =
-        fn_sig.zip(projection).and_then(|(sig, p)| match p.self_ty().kind() {
+        fn_sig.zip(projection).and_then(|(sig, p)| match *p.self_ty().kind() {
             // Shenanigans to get the `Trait` from the `impl Trait`.
             ty::Param(param) => {
                 let param_def = generics.type_param(param, tcx);
@@ -252,7 +252,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         let trait_pred = self.resolve_numeric_literals_with_default(trait_pred);
 
         let self_ty = trait_pred.skip_binder().self_ty();
-        let (param_ty, projection) = match self_ty.kind() {
+        let (param_ty, projection) = match *self_ty.kind() {
             ty::Param(_) => (true, None),
             ty::Alias(ty::Projection, projection) => (false, Some(projection)),
             _ => (false, None),

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -482,7 +482,7 @@ fn is_impossible_associated_item(
         type Result = ControlFlow<()>;
         fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
             // If this is a parameter from the trait item's own generics, then bail
-            if let ty::Param(param) = t.kind()
+            if let ty::Param(param) = *t.kind()
                 && let param_def_id = self.generics.type_param(param, self.tcx).def_id
                 && self.tcx.parent(param_def_id) == self.trait_item_def_id
             {
@@ -492,7 +492,7 @@ fn is_impossible_associated_item(
         }
         fn visit_region(&mut self, r: ty::Region<'tcx>) -> Self::Result {
             if let ty::ReEarlyParam(param) = r.kind()
-                && let param_def_id = self.generics.region_param(&param, self.tcx).def_id
+                && let param_def_id = self.generics.region_param(param, self.tcx).def_id
                 && self.tcx.parent(param_def_id) == self.trait_item_def_id
             {
                 return ControlFlow::Break(());
@@ -501,7 +501,7 @@ fn is_impossible_associated_item(
         }
         fn visit_const(&mut self, ct: ty::Const<'tcx>) -> Self::Result {
             if let ty::ConstKind::Param(param) = ct.kind()
-                && let param_def_id = self.generics.const_param(&param, self.tcx).def_id
+                && let param_def_id = self.generics.const_param(param, self.tcx).def_id
                 && self.tcx.parent(param_def_id) == self.trait_item_def_id
             {
                 return ControlFlow::Break(());

compiler/rustc_ty_utils/src/opaque_types.rs

@@ -130,7 +130,7 @@ impl<'tcx> OpaqueTypeCollector<'tcx> {
         TaitInBodyFinder { collector: self }.visit_expr(body);
     }
 
-    fn visit_opaque_ty(&mut self, alias_ty: &ty::AliasTy<'tcx>) {
+    fn visit_opaque_ty(&mut self, alias_ty: ty::AliasTy<'tcx>) {
         if !self.seen.insert(alias_ty.def_id.expect_local()) {
             return;
         }
@@ -205,7 +205,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
     #[instrument(skip(self), ret, level = "trace")]
     fn visit_ty(&mut self, t: Ty<'tcx>) {
         t.super_visit_with(self);
-        match t.kind() {
+        match *t.kind() {
             ty::Alias(ty::Opaque, alias_ty) if alias_ty.def_id.is_local() => {
                 self.visit_opaque_ty(alias_ty);
             }
@@ -279,7 +279,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
                     // assumption to the `param_env` of the default method. We also separately
                     // rely on that assumption here.
                     let ty = self.tcx.type_of(alias_ty.def_id).instantiate(self.tcx, alias_ty.args);
-                    let ty::Alias(ty::Opaque, alias_ty) = ty.kind() else { bug!("{ty:?}") };
+                    let ty::Alias(ty::Opaque, alias_ty) = *ty.kind() else { bug!("{ty:?}") };
                     self.visit_opaque_ty(alias_ty);
                 }
             }